import tkinter as tk

root = tk.Tk()
root.geometry('200x200')

def close_window():
    root.destroy()

close_bt = tk.Button(root, text = 'close', command = close_window)
close_bt.pack()

def disable_close_bt():
    return

root.protocol('WM_DELETE_WINDOW', disable_close_bt)
root.mainloop()